This was given by a thermometer only placed in the cave at 7 P.M., and by construction not very sensible.
The moment when the disturbance of the atmosphere commenced.
M. Thury gives—4°·62 C. as the minimum in the glacière during the night in question; but on the next page he gives—6°·8 C. (=19°·76 F.). It is evident, from a comparison with other details of his observations, that the latter is the correct account.